import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleep


def check_keydown_events(event, ai_settings, screen, ship, bullets):
    "响应按键"
    if event.key == pygame.K_RIGHT:
        ship.moving_right = True
    elif event.key == pygame.K_LEFT:
        ship.moving_left = True
    elif event.key == pygame.K_SPACE:
        # 创建一颗子弹，并将其加入到编组bullets中
        # if len(bullets) < ai_settings.bullets_allowed:
        #     new_bullet = Bullet(ai_settings, screen, ship)
        #     bullets.add(new_bullet)
        fire_bullet(ai_settings, screen, ship, bullets)
    elif event.key == pygame.K_q:
        sys.exit()

def check_keyup_events(event, ship):
    "响应松开"
    if event.key == pygame.K_RIGHT:
        ship.moving_right = False
    elif event.key == pygame.K_LEFT:
        ship.moving_left = False

def check_events( ai_settings, screen, stats, sb, play_button, ship, aliens, bullets):
    "响应按键和鼠标事件"
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()
        elif event.type == pygame.KEYDOWN:
            check_keydown_events(event, ai_settings, screen, ship, bullets)
        elif event.type == pygame.KEYUP:
            check_keyup_events(event, ship)
        elif event.type == pygame.MOUSEBUTTONDOWN:
            mouse_x, mouse_y = pygame.mouse.get_pos()
            check_play_button(ai_settings, screen ,stats, sb, play_button, ship, aliens, bullets, mouse_x, mouse_y)

def check_play_button(ai_settings, screen ,stats, sb, play_button, ship, aliens, bullets, mouse_x, mouse_y):
    "在玩家单击play按钮时开始新游戏"
    button_clicked = play_button.rect.collidepoint(mouse_x, mouse_y)

    if button_clicked and not stats.game_active:
        # 重置游戏设置
        ai_settings.initialize_dynamic_settings()

        # 隐藏光标
        pygame.mouse.set_visible(False)

        # 重置游戏统计信息
        stats.reset_stats()
        stats.game_active = True
#         重置记分牌图像
        sb.prep_score()
        sb.prep_high_score()

        sb.prep_level()
        sb.prep_ships()
#         清空外星人列表和子弹列表
        aliens.empty()
        bullets.empty()
#         创建一群新的外星人，并让飞穿剧中
        create_fleet(ai_settings, screen, ship, aliens)
        ship.center_ship()

def update_screen(ai_settings, screen, stats,sb, ship, aliens, bullets, play_button):
    "更新屏幕上的图像，并切换到新屏幕"

    # 每次循环时都重绘屏幕
    screen.fill(ai_settings.bg_color)

    # 在飞船和外星人后面重绘所有子弹
    for bullet in bullets.sprites():
        bullet.draw_bullet()

    ship.blitme()
    aliens.draw(screen)
    # 显示得分
    sb.show_score()
    # 如果游戏处于非活动状态，就绘制play按钮
    if not stats.game_active:
        play_button.draw_button()
    # 让最近绘制的屏幕可见
    pygame.display.flip()

def update_bullets(ai_settings, screen,stats,sb, ship, aliens, bullets):
    "更新子弹的位置，并删除已消失的子弹"
    # 更新子弹的位置
    bullets.update()
    # 删除已消失的子弹
    for bullet in bullets.copy():
        if bullet.rect.bottom <= 0:
            bullets.remove(bullet)
    check_bullet_alien_collisions(ai_settings, screen,stats,sb, ship, aliens, bullets)

def check_bullet_alien_collisions(ai_settings, screen, stats,sb, ship, aliens, bullets):
    "响应子弹和外星人的碰撞"
    # 删除发生碰撞的子弹和外星人
    # 检测是否有子弹击中了外星人
    collisions = pygame.sprite.groupcollide(bullets, aliens, True, True)
    if collisions:
        for aliens in collisions.values():

            stats.score+=ai_settings.alien_points*len(aliens)
            sb.prep_score()
        # 更新最高分
        check_high_score(stats, sb)

    if len(aliens) == 0:
        # 删除现有的子弹,加快游戏节奏，并新建一群外星人
        bullets.empty()
        ai_settings.increase_speed()
        # 提高等级
        stats.level+=1
        sb.prep_level()
        create_fleet(ai_settings, screen, ship, aliens)
# 开火
def fire_bullet(ai_settings, screen, ship, bullets):
    "如果还没有达到限制，就发射一颗子弹"
    # 创建新子弹，并将其加入到编组bullets中
    if len(bullets) < ai_settings.bullets_allowed:
        new_bullet = Bullet(ai_settings, screen, ship)
        bullets.add(new_bullet)


def get_number_aliens_x(ai_settings, alien_width):
    "计算每行可容纳多少外星人"
    available_space_x = ai_settings.screen_width - 2 * alien_width
    number_aliens_x = int(available_space_x/(2*alien_width))
    return number_aliens_x

def get_number_rows(ai_settings, ship_height, alien_height):
    "计算屏幕可容纳多少行外星人"
    available_space_y = (ai_settings.screen_height - (3*alien_height) - ship_height)
    number_rows = int(available_space_y / (2*alien_height))
    return number_rows

def create_alien(ai_settings, screen, aliens, alien_number, row_number):
    "创建一个外星人并将其放在当前行"
    alien = Alien(ai_settings, screen)
    alien_width = alien.rect.width
    alien.x = alien_width+2*alien_width*alien_number
    alien.rect.x = alien.x
    alien.rect.y = alien.rect.height+2*alien.rect.height*row_number
    aliens.add(alien)




def create_fleet(ai_settings, screen, ship, aliens):
    "创建外星人群"
    # 创建一个外星人，并计算一行可以容纳多少个外星人
    # 外星人的间距为外星人的宽度
    alien = Alien(ai_settings, screen)
    alien_width = alien.rect.width
    number_aliens_x = get_number_aliens_x(ai_settings, alien_width)
    number_rows = get_number_rows(ai_settings, ship.rect.height,alien.rect.height)

    # 创建外星人qun
    for row_number in range(number_rows):
        for alien_number in range(number_aliens_x):
            create_alien(ai_settings, screen, aliens, alien_number, row_number)
def check_aliens_bottom(ai_settings,screen, stats, sb, ship, aliens, bullets):
    "检测是否有外星人到达屏幕低端"
    screen_rect = screen.get_rect()
    for alien in aliens.sprites():
        if alien.rect.bottom >= screen_rect.bottom:
#             像飞船被撞到一样处理
            ship_hit(ai_settings,screen, stats, sb, ship, aliens, bullets)
            break
def ship_hit(ai_settings,screen, stats,sb, ship, aliens, bullets):
    "响应被外星人撞到的飞船"
#     将ships_left-1
    if stats.ships_left > 0:

        stats.ships_left-=1
    #     更新记分牌
        sb.prep_ships()
    #     清空外星人列表和子弹列表
        aliens.empty()
        bullets.empty()
    #     创建一群新的外星人，并将飞船放到屏幕低端中央
        create_fleet(ai_settings, screen, ship, aliens)
        ship.center_ship()
        sleep(0.5)
    else:

        stats.game_active = False
        pygame.mouse.set_visible(True)

def update_aliens(ai_settings,screen, stats, sb, ship, aliens,bullets):
    "更新外星人群中所有外星人的位置"
    "检测是否有外星人位于屏幕边缘，并更新整群外星人的位置"
    check_fleet_edges(ai_settings, aliens)
    aliens.update()
    # 检测外星人和飞船之间的碰撞
    if pygame.sprite.spritecollideany(ship, aliens):
        ship_hit(ai_settings,screen, stats,sb, ship, aliens, bullets)
    # 检测是否有外星人到达屏幕底端
    check_aliens_bottom(ai_settings, screen, stats, sb, ship, aliens, bullets)
def change_fleet_direction(ai_settings, aliens):
    "将整群外星人下移，并改变他们的方向"
    for alien in aliens.sprites():
        alien.rect.y += ai_settings.fleet_drop_speed
    ai_settings.fleet_direction *= -1

def check_fleet_edges(ai_settings, aliens):
    "有外星人到达边缘时采取相应的措施"
    for alien in aliens.sprites():
        if alien.check_edges():
            change_fleet_direction(ai_settings, aliens)
            break


def check_high_score(stats, sb):
    "检测是否诞生了新的最高分"
    if stats.score > stats.high_score:
        stats.high_score = stats.score
        sb.prep_high_score()